Atmospheric chemistry, sources and sinks of carbon suboxide, Csub3/subOsub2/sub

摘要

Carbon suboxide, O??=??C??=??C??=??C??=??O, has been detected in ambient air samples and has the potential to be a noxious pollutant and oxidant precursor; however, its lifetime and fate in the atmosphere are largely unknown. In this work, we collect an extensive set of studies on the atmospheric chemistry of Csub3/subOsub2/sub. Rate coefficients for the reactions of Csub3/subOsub2/sub with OH radicals and ozone were determined as ik/isubOH/sub?=??(2.6?±?0.5)??×??10sup?12/sup?cmsup3/sup?moleculesup?1/sup?ssup?1/sup at 295?K (independent of pressure between ?～??25 and 1000?mbar) and ik/isubOsub3/sub/sub??&??1.5??×??10sup?21/sup?cmsup3/sup?moleculesup?1/sup?ssup?1/sup at 295?K. A theoretical study on the mechanisms of these reactions indicates that the sole products are CO and COsub2/sub, as observed experimentally. The UV absorption spectrum and the interaction of Csub3/subOsub2/sub with water (Henry's law solubility and hydrolysis rate constant) were also investigated, enabling its photodissociation lifetime and hydrolysis rates, respectively, to be assessed. brbr The role of Csub3/subOsub2/sub in the atmosphere was examined using in situ measurements, an analysis of the atmospheric sources and sinks and simulation with the EMAC atmospheric chemistry–general circulation model. The results indicate sub-pptv levels at the Earth's surface, up to about 10?pptv in regions with relatively strong sources, e.g. influenced by biomass burning, and a mean lifetime of ?～??3.2?days. These predictions carry considerable uncertainty, as more measurement data are needed to determine ambient concentrations and constrain the source strengths.